Development of a performance-derived nutritional value for a microencapsulated gut health additive from a...

Feed additives targeting gut health are widely used to improve efficiency in broilers, yet their nutritional value is rarely quantified, especially when containing ingredients like botanicals and organic acids. The objective of the study was to develop a nutritional value for a microencapsulated blend of botanicals and organic acids (mBOA; AviPlus^®P) and validate the approach in vivo. A meta-analysis of 35 trials (2009-2022) was carried out comparing mBOA at 200-500 mg/kg vs. control groups, both under non-medicated cereal-soy diets for durations spanning 34-48 days. Random-effects (REML) models summarized effects on final body weight (FBW) and standardized feed conversion (FCRst). Across studies, mBOA increased FBW (+38 g; P = 0.009) and improved FCRst (-0.04 points; P = 0.001). The observed performance gains were back-converted into dietary energy and protein equivalences to parameterize a performance-derived nutritional value for mBOA at 300 mg/kg, resulting in 60.58 kcal of Metabolizable Energy (ME) and 3.88 g of crude protein (CP) per kg of diet. The nutritional value was then tested in 810 Ross 308 males (15 pens/treatment) allocated into three groups: (1) a group fed with a standard diet (STD), (2) a group fed with a reformulated diet (REF = -80 kcal ME/kg and -2% CP and digestible amino acids), and (3) a group fed with the same reformulated diet and supplemented with mBOA at 300 mg/kg (APP). Overall (d 0-41), REF showed higher average daily feed intake (ADFI) and worse feed conversion ratio (FCR) than STD (1.56 vs. 1.53), while APP was intermediate (1.54) and numerically closer to STD (P = 0.003). APP improved CP digestibility compared to STD (P = 0.038) and fat digestibility to REF (P < 0.001), partially restoring AMEn (APP 2852 vs. REF 2827 vs. STD 2873 kcal/kg DM; P = 0.003). The findings obtained using this multi-step approach support the application of mBOA to partially offset reduced-density formulations without compromising efficiency, providing formulation-ready values for broiler diets.